I’m not having much luck with my tank lost a bunch of fish at start for no reason I can think of my numbers are 0-0-25 or less after water change on the nitrates. My tetras are fine now after I lost 13 of 17 the other 4 seem to be happy. My problem are with my corydoras they just seem to hide all the time the move a lot during a water change or at night they tend to come out some but I never see them during the day unless I look real hard for them. My reason for getting them is their suppose to be active they where the main fish I wanted in my tank. The biggest thing that aggravates me is when I kept tanks in the past I would fill it with water put some declorinator in it and drop the fish in. I know that was very wrong but I didn’t know any better but my fish always seem to last and thrive then and this time did the full cycle and made sure all was good and can’t seem to get nothing to work.